Ligands used in affinity chromatography typically confer a high selectivity for the target molecule, thereby resulting in high yield and fast and economical purification of target molecules. Staphylococcal protein A (SpA) based reagents and chromatography matrices have found a widespread use in the field of affinity chromatography for capture and purification of antibodies as well as in antibody detection methods due to its ability to bind IgG without significantly affecting the affinity of the immunoglobulin for antigen.
Accordingly, various reagents and media comprising protein A-ligands have been developed and are commercially available including, for example, ProSep®-vA High Capacity, ProSep® vA Ultra and ProSep® UltraPlus (Millipore) and Protein A Sepharose™, MabSelect™, MabSelect Xtra™ and MabSelect SuRe® (GE Healthcare) and Poros MabCapture A™ (Applied Biosystems).
In order to maintain selectivity and binding capacity of the chromatography ligands including, e.g., resins including SpA based chromatography ligands, the ligand bound resins, referred to as chromatography matrices, have to be cleaned and are typically cleaned under alkaline conditions, e.g., with sodium hydroxide. For example, a standard process which is used for cleaning and restoring the matrix is a cleaning-in-place (CIP) alkaline protocol, which typically involves treatment of the matrix with 1M NaOH, pH 14. However, such harsh treatment is often undesirable, especially, where the ligand is a protein or a protein-based molecule.